Direct computation of characteristic temperatures and relaxation times for glass-forming polymer liquids

2005 ◽  
Vol 123 (11) ◽  
pp. 111102 ◽  
Author(s):  
Jacek Dudowicz ◽  
Karl F. Freed ◽  
Jack F. Douglas
Keyword(s):  
Relaxation Times ◽  
Direct Computation ◽  
Glass Forming ◽  
Characteristic Temperatures ◽  
Polymer Liquids

A criterion of glass-forming ability and stability derived from pseudo-four characteristic temperatures

2021 ◽  
Vol 134 ◽  
pp. 107201
Author(s):  
Xiaocheng Li ◽  
Shengzhong Kou ◽  
Chunyan Li ◽  
Yanchun Zhao ◽  
Yutian Ding
Keyword(s):  
Glass Forming Ability ◽  
Glass Forming ◽  
Characteristic Temperatures

Phosphotellurite glass and glass-ceramics with high TeO2 contents: thermal, structural and optical properties

2019 ◽  
Vol 48 (18) ◽  
pp. 6261-6272 ◽  
Author(s):  
Danilo Manzani ◽  
João B. Souza Junior ◽  
Albert S. Reyna ◽  
Manoel L. Silva Neto ◽  
Jessica E. Q. Bautista ◽  
...  
Keyword(s):  
Optical Properties ◽  
Glass Ceramics ◽  
Glass Forming Ability ◽  
Transparency Window ◽  
Structural And Optical Properties ◽  
Glass Forming ◽  
Characteristic Temperatures

Phosphotellurite based glasses and glass-ceramics have interesting features such as low characteristic temperatures, high glass forming ability, promising optical properties and a broad transparency window from UV to NIR.

Static lengths in glass-forming monodisperse hard-sphere fluids from periodic array pinning

Soft Matter ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 402-407 ◽  
Author(s):  
Yuxing Zhou ◽  
Scott T. Milner
Keyword(s):  
Structural Relaxation ◽  
Hard Sphere ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Relaxation Times ◽  
Periodic Array ◽  
Length Scale ◽  
Master Curves ◽  
Particle Volume ◽  
Glass Forming

In glassy hard-sphere fluids, with varying particle volume fraction and distance between pinned particles, particle diffusivities and structural relaxation times both collapse to master curves, revealing a growing static length scale.

COOPERATIVE FREE VOLUME RATE MODEL APPLIED TO THE PRESSURE-DEPENDENT SEGMENTAL DYNAMICS OF NATURAL RUBBER AND POLYUREA

2019 ◽  
Vol 92 (4) ◽  
pp. 612-624
Author(s):  
Ronald P. White ◽  
Jane E. G. Lipson
Keyword(s):  
Natural Rubber ◽  
Free Volume ◽  
Relaxation Times ◽  
Close Packing ◽  
Rate Model ◽  
Segmental Dynamics ◽  
Glass Forming ◽  
Segmental Relaxation ◽  
The Difference ◽  
New Applications

ABSTRACT We apply the cooperative free volume (CFV) rate model for pressure-dependent dynamics of glass-forming liquids and polymer melts, focusing on two new applications of the model, to natural rubber and to polyurea. In CFV, segmental relaxation times, τ, are analyzed as a function of temperature (T) and free volume (Vfree), where the latter provides an insightful route to expressing dynamics relative to using the system's overall total volume (V). Vfree is defined as the difference between the total volume and the volume at close packing and is predicted independently of the dynamics for any temperature and pressure using the locally correlated lattice equation-of-state analysis of characteristic thermodynamic data. The new results for natural rubber and polyurea are discussed in the context of results on a set of polymeric and small-molecule glass formers that had previously been modeled with CFV. We also discuss the results in the context of recent connections that we have made with the density-scaling approach.

scholarly journals A Novel Viscosity-Temperature Model of Glass-Forming Liquids by Modifying the Eyring Viscosity Equation

2020 ◽  
Vol 10 (2) ◽  
pp. 428 ◽  
Author(s):  
Chunyu Chen ◽  
Huidan Zeng ◽  
Yifan Deng ◽  
Jingtao Yan ◽  
Yejia Jiang ◽  
...  
Keyword(s):  
Mathematical Expression ◽  
Impact Factors ◽  
Viscosity Data ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Regression Methods ◽  
Glass Forming ◽  
Viscosity Models ◽  
Polymer Liquids ◽  
Dependent Viscosity

Many models have been created and attempted to describe the temperature-dependent viscosity of glass-forming liquids, which is the foundational feature to lay out the mechanism of obtaining desired glass properties. Most viscosity models were generated along with several impact factors. The complex compositions of commercial glasses raise challenges to settle these parameters. Usually, this issue will lead to unsatisfactory predicted results when fitted to a real viscosity profile. In fact, the introduction of the reliable viscosity-temperature data to viscosity equations is an effective approach to obtain the accurate parameters. In this paper, the Eyring viscosity equation, which is widely adopted for molecular and polymer liquids, was applied in this case to calculate the viscosity of glass materials. On the basis of the linear variation of molar volume with temperature during glass cooling, a modified temperature-dependent Eyring viscosity equation was derived with a distinguished mathematical expression. By means of combining high-temperature viscosity data and the glass transition temperature (Tg), nonlinear regression analysis was employed to obtain the accurate parameters of the equation. In addition, we have demonstrated that the different regression methods exert a great effect on the final prediction results. The viscosity of a series of glasses across a wide temperature range was accurately predicted via the optimal regression method, which was further used to verify the reliability of the modified Eyring equation.

scholarly journals Testing the paradigm of an ideal glass transition: Dynamics of an ultrastable polymeric glass

2018 ◽  
Vol 4 (12) ◽  
pp. eaau5423 ◽  
Author(s):  
Heedong Yoon ◽  
Gregory B. McKenna
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glassy State ◽  
Relaxation Times ◽  
Fictive Temperature ◽  
Transition Dynamics ◽  
Kauzmann Temperature ◽  
Glass Forming ◽  
Equilibrium Data ◽  
Glass Forming Materials

A major challenge to understanding glass-forming materials is obtaining equilibrium data far below the laboratory glass transition temperatureTg. The challenge arises because it takes geologic aging times to achieve the equilibrium glassy state when temperatures are well belowTg. Here, we finesse this problem through measurements on an ultrastable amorphous Teflon with fictive temperatureTfnear to its Kauzmann temperatureTK. In the window betweenTfandTg, the material has a lower molecular mobility than the equilibrium state because of its low specific volume and enthalpy. Our measurements show that the determined scaled relaxation times deviate strongly from the classical expectation of divergence of time scales at a finite temperature. The results challenge the view of an ideal glass transition at or near toTK.

Correlation Between Thermodynamic and Kinetic Properties of Glass-Forming Liquids

2007 ◽  
Vol 1048 ◽  
Author(s):  
Oleg N. Senkov ◽  
Daniel B. Miracle
Keyword(s):  
Glass Transition ◽  
Geometric Mean ◽  
Configurational Entropy ◽  
Excess Heat Capacity ◽  
Kinetic Properties ◽  
Vibrational Entropy ◽  
Glass Forming ◽  
Characteristic Temperatures ◽  
Higher Temperature ◽  
Glass Forming Materials

AbstractCorrelations between three characteristic temperatures: glass transition, Tg, Kauzmann, Tk, and Vogel-Fulcher-Tammann, To, were identified from the analysis of more than 60 metallic and non-metallic glass-forming materials. It was found that Tg ≥ Tk ≥ To and Tk is the geometric mean of Tg and To. The relation Tk ≥ To indicates that the excess total entropy of a super-cooled liquid ΔS approaches zero at a higher temperature than the configurational entropy ΔSconf, and such behavior was explained by the stronger temperature dependence of the excess vibrational entropy of the liquid, ΔSvib, than that of the corresponding glass, . A relationship between the fragility index m, reduced excess heat capacity ΔCp(Tg)/Sm, and reduced glass transition temperature, Trg, was identified using the found correlation between the characteristic temperatures.

Sign in / Sign up

Export Citation Format

Share Document